The benefits of using object
identifiers for quantities and units in
human physiology
Jean-Paul Lemaire
Associate Rapporteur of ITU-T SG 17/Q.9 (Telebiometrics)
ITU-T Workshop on “Radioactivity safety and security threats
protection and telemedical support for irradiated people”
Geneva 30 Aug 2011
Summary
This presentation explains how object identifiers
and ASN.1 can be used in data exchange in
telemedicine which is very useful in radioprotection
when areas are potentially contaminated :
• Object identifiers can identify unambiguously quantities,
units and symbols.
• ASN.1 can be used to define objects equivalent to
tables but directly usable by applications.
• ASN.1 is also useful to describe messages and
provides several encoding rules.
Object identifiers
• Object
identifiers have been designed to assign
unambiguous identifiers to many kinds of objects involved
in telecommunications:
• network management
• directory systems (object classes, attributes, etc).
• Object identifiers are now defined in ITU-T X.660 series of
ITU-T Recommendations and ISO/IEC 9834 standard.
• The object identifiers are organized in a hierarchical
structure administered by ITU-T and ISO: the first level
contains three arcs:
• arc 0: itu-t, administered by ITU-T
• arc 1: iso, administered by ISO
• arc 2: joint-iso-itu-t, administered jointly by ITU-T and ISO.
The first arcs of the registration tree
root
iso(1)
itu-t(0)
recommendation(0)
a(1)
standard(0)
member-body(2)
joint-iso-itu-t(2)
asn1(1)
ds(5)
z(26)
An object identifier is defined by the list of the arcs from the root.
Each arc can be defined by a number or a number and an identifier:
• in ASN.1 notation: {itu-t(0) recommendation(0) a(1)}
• in dot notation: 0.0.1.
Another notation: OID-IRI
• The ASN.1 and dot notations have been completed by a
new one, OID-IRI which allows usage of humanfriendly notation not limited to latin alphabets but which
allows Unicode alphabets.
• An OID-IRI is a list of Unicode labels separated by /
characters:
/ITU-T/Recommendation for {itu-t(0) recommendation(0)}
/ISO/Member-Body for {iso(1) member-body(2)}
• With OID-IRI, it is possible to define “long arcs” which
are Unicode labels which permits, in the joint-iso-itu-t
branch, to access directly OIDs not immediately
beneath the root.
The Telebiometrics subtree
For telebiometrics and e-health, a specific OID branch has been
defined: {joint-iso-itu-t(2) telebiometrics(42)} with the associated long
measures(1)
arc /Telebiometrics
Measures
tmm(1)
TMM
human-physiology(2)
Human_Physiology
telehealth-protocol(3)
Telehealth_Protocol
{2 42}
Telebiometrics
physics(4)
Th_Physics
chemistry(5)
Th_Chemistry
biology(6)
Th_Biology
culturology(7)
Th_Culturology
psychology(8)
Th_psychology
patients(1)
Patients
medical-staff(2)
Medical_Staff
observers(3)
Observers
pharmaceutical-staff(4)
Pharmaceutical_Staff
laboratories(5)
Laboraties
drug-manufacturers(6)
Drug_Manufacturers
medical-device(7)
Medical_Device
medical-software(8)
Medical_Software
medical-insurance(9)
Medical_Insurance
medical-records(10)
Medical_Records
The risks in e-health
There are several risks in e-heath:
• risks in data transmission:
• modification of data during transmission
• divulgation of private information
They are covered by e-health-protocol (X.th1, future X.1080.1).
• risks in misinterpretation of data:
• great number of quantities particularly in chemistry and biology
• Several units and symbols associated to a given quantity.
They are covered by using unique object identifiers for quantities,
units and symbols. These object identifiers will be defined in the five
specific parts of X.th series:
• X.th2 (physics)
• X.th4 (biology)
• X.th6 (psychology)
• X.th3 (chemistry)
• X.th5 (culturology)
Object identifiers assigned to quantities,
units and symbols
physics(1)
Physics
quantities(1)
Quantities
chemistry(2)
Chemistry
biology(3)
Biology
culturology(4)
Culturology
{2 42 1 1}
/Telebiometrics/TMM/Measures
units(2)
Units
symbols(3)
Symbols
psychology(5)
Psychology
Definitions of quantities
Each quantity is defined using the ASN.1
information object class QUANTITY which
defines:
• the name (in English and optionally in French)
• the associated symbols defined by a name, an object
identifier completed by a RELATIVE-OID-IRI
• the unit
• the modalities
• the assigned object identifier completed
RELATIVE-OID-IRI.
by
a
Example of quantity
The sodium element is defined as follows:
sodium
QUANTITY ::= {
"sodium" USING SYMBOLS {
{"Na"} IDENTIFIED BY
{id-symbols sodium(11)}
AND "Na"}
MEASURED IN {percent} FOR MODALITIES
{id-tango}
IDENTIFIED BY
{id-quantities sodium(11)}
AND "Sodium" }
Example of quantity
The definition specifies:
• the name of the object
• the symbol “Na” with an object identifier
completed by a RELATIVE-OID-IRI
• the unit defined as informational object
percent, the modalities and the associated
object identifier completed by a RELATIVEOID-IRI.
Definitions of units
Each unit is defined using the ASN.1
information object class UNIT which defines:
• the name (in English and optionally in French)
• the associated symbol
• the assigned object identifier and RELATIVE-
OID-IRI.
• the other units from which this unit is derived
A unit which is a multiple or submultiple of a
another one (for example millimeter) is related to
basic unit with a factor which is a power of 10.
Example of unit
The kg/l is defined as follows:
kilogramPerLitre UNIT ::= {
"kilogramPerLitre" USING SYMBOLS {
{{"kg . l" , superscriptMinus ,
superscriptOne}}
IDENTIFIED BY {id-symbols kilogramPerLitre(0)}
AND "KilogramPerLitre"}
IDENTIFIED BY {id-units kilogramPerLitre(1)}
AND "KilogramPerLitre"
DERIVED BY PRODUCT OF {kilogram}
DIVIDED BY {litre}}
Example of unit
This definition specifies:
• the name kilogramPerLitre
• the
associated symbol kg.l-1 with the
corresponding object identifier and RELATIVEOID-IRI
• the
object identifier completed by the
RELATIVE-OID-IRI. Its also specifies that this
unit is derived from two other units kilogram
and litre.
Definition of symbols
A symbol is defined by:
• One or more character string
• The attributes of the strings (for example italic)
• the assigned object identifier completed by a
RELATIVE-OID-IRI.
Example:
sodium-symbol SYMBOL ::=
{{"Na"} IDENTIFIED BY {id-symbols sodium(11)} AND
"Na"}
Relations between quantities units and
symbols
• The information objects related to quantities and symbols
are linked together so starting from a quantity, it is
possible to find the possible units and symbols.
• The multiples and submultiples of a unit are also linked to
the base unit.
Quantities
Physics
Chemistry
Biology
Culturology
psychology
Units
Symbols
Conclusion
The definition of object identifiers for quantities and
units enforces the reliability and security of medical
data transmission because they can be
automatically processed and imported from a
unique repository (which does not exist
nowadays).
They also permit the presentation of test results in
various forms and conform to the usages of the
medical practitioners because the symbols and
multiples or submultiples of basic units are
included in the informational object definitions.